RECENT WORK IN AGRICULTURAL SCIENCE. 



AGRICULTUKAL CHEMISTRY— AGKOTECHNY. 



The fermenting- capacity of the average single cell of Bacterium lactis 

 acidi, O. Rahn (Michigan Sta. Tech. Bui. 10, pp. 3-40, fig. !)■ — By noting the 

 number of bacteria with the usual plating method at the beginning and end of 

 the experimental period it is possible to estimate the amount of acid formed 

 by a single bacterial cell in 1 hour. The figure thus obtained will be suffi- 

 ciently accurate to detect any variation in the fermenting power of the micro- 

 organism. 



The loop-actual-microscopic method of counting was found entirely unsatis- 

 factory for such work, since many of the counts showed a decrease in the total 

 number of micro-oi'ganisms after propagation. Actually counting the micro- 

 organisms by the plate method is considered a better basis than ascertaining the 

 weight of the bacteria and computing the fermenting capacity therefrom. 



" The amount of acid formed by one cell in one hour was found to be in 

 young milk cultures in the average of 57 determinations with various strains, 

 0.0.000,000,018 mg. or 18X10"'" mg. This is approximately the weight of one 

 single cell. There is no experiment on record to prove that iu the first stage 

 of development the multiplication takes place without fermentation [as is 

 asserted by several authors]. As soon as a determination of fermentation 

 products is possible, it shows the fermentation per cell to be the faster the 

 younger the culture. There is a distinct difference in the fermenting capacity 

 of different strains. The weakest strain had an average fermenting capacity 

 of 7.4X10"'", while the strongest strain averaged 32.5X10"'" mg. per cell and 

 hour. 



" The fermenting capacity decreases with the age of the culture, and even if 

 the acid is neutralized the fermenting capacity is lower though fermentation 

 takes place again. Old cultures acidify slowly, even if transferred into fresh 

 milk, the rate of multiplication is also influenced by long sojourn in the same 

 culture. Peptone stimulates the acid formation of certain strains, but only 

 by increasing their numbers while the amounts of acid per cell remain un- 

 altered. Other strains show no material influence of peptone. In sugar-free 

 broth they develop very slowly, but the fermenting capacity is normal if lactose 

 is added. Temperature influences the fermenting capacity very decidedly." 



The use of sodium paratungstate in the determination of carbon dioxid 

 in carbonates and nitrogen pentoxid in nitrates by loss on ignition, F. A. 

 GoocH and S. B. Kuzirian {Amcr. Jour. 8ci., Jf. so:, 31 (1911), No. 1S6, pp. 

 1/97-500). — "From the results of the experiments described ... it is obvious 

 that sodium paratungstate, easily prepared and stable, makes an excellent flux 

 for use in the rapid determination of carbon dioxid and of nitrogen pentoxid by 

 loss on ignition." 



In regard to titrating phosphates, W. Streckeb and P. Schiffer (Ztschr. 

 Analyf. Chcm., 50 (1911), No. S, pp. //y5-//9.0).— Comparative tests made betweeu 

 the uranyl acetate and silver nitrate methods show that both of them, when 

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